1. Field of the Invention
The use of bitumens (i.e., asphalt and cold tar) for roofing and other applications is well known. The advantage of cold applicability, e.g. on flat roofs so as to avoid working with a hot material at a job site is also well known. It is desirable to achieve improved formulations to increase the economy of the effort and improve the properties of the treated materials.
2. Description of the Background Art
U.S. Pat. No. 5,840,105 discloses the use of bentonite from drilling muds for sodium silicate and fine mica coatings. U.S. Pat. No. 5,970,893 discloses clay liners as barriers for the containment of pollutants or toxic waste.
It has now been found that aqueous emulsions of specific drilling mud bentonite with bitumen provide formulations that have markedly decreased costs and markedly improved properties for cold application. It is surprising to find that this specialty bentonite provides such superior results outside the petroleum drilling mud field.
The drilling bentonite mud conform to American Petroleum Institute (API) specification 13A which yield approximately 120 to 280 barrels of 15 centiposes mud per ton, preferably about 180 to 240 barrels per ton. Typical bentonites with their trademarks Hydraul-EZ; KWIK-THIK and Super-Gel-X.
Asphalt is a bitumen derived from a number of materials such as, for example, petroleum, shale oil, gilsonite and the like. Asphalt is a thick, viscous mixture of compounds such as, for example, paraffinic, cycloaliphatic and aromatic hydrocarbon and lesser amounts of heterocylic compound containing sulfur, nitrogen or oxygen. Although asphalt can be obtained from natural sources, it is primarily derived as the residue of petroleum distillation (e.g., the bottom product of a vacuum distillation of a topped crude). Although this invention is not limited thereto, it is preferred that the asphalt have a penetration (ASTM D5) at 77 degrees F. dmm: ranging from about 5 to about 300 dmm and more preferably from about 50 to about 200 dmm and conform in general to specification outlined by ASTM D312, D946 and/or D449.
The asphalt can be utilized in the form of an aqueous emulsion readily available in the trade, see ASTM D1227, and thus has a water content of about 40-60 wt.%.
Coal tar is a bitumen derived from crude coal tar, water gas tar, oil gas tar or from combination of such tars with their constituents. Coal tar is a black, viscous, naphthalene-like odor, amorphous residue mainly from distillation of coal. The majority of its composition is polynuclear aromatic compounds such a aromatic hydrocarbon, naphthalenic, phenolic, anthracenic, quinolinic compound with trace of insoluble materials. Different grades have different float tests and softening points. Although this invention is not constrained to, the preferred coal tars have a float test at 122 degrees F., seconds: ranging from about 75 to bout 230 seconds and more preferably from about 180 to 220 seconds and conform in general to specification outlined by RT-10 (Road tar-10) RT-11 and RT-12 in ASTM D490.
The coal tar can be utilized in the form of an aqueous emulsion readily available in the trade (see Federal Specification RP 355e) and thus has a maximum water content of about 53 wt. %.
At least one of asphalt and coal tar are employed, depending on desired final product.
Subject to the foregoing, the ranges of components are about:
The specialty additives include e.g. mineral salt to increase emulsability; complex organic acids such as acetic acid etc. to bring the pH to a range of 4-6, also to enhance emulsability, and polymers singly or in combination for a similar purpose, e.g. acrylic, vinyl polystyrene, etc.
Inert fillers such as pulverized limestone powder, talc, perlite, etc., can be used in an amount of about 0 to 50, wt. %.
Inert fibers such as cellulosic, asbestos, fiberglass, polyolefin, etc. can be used in an amount of from about 0-25 wt. %.
It should be noted that the amount of water listed above is in addition to that derived from asphalt and cold tar aqueous emulsions employed.
The process of producing the aqueous emulsified bitumens are as follows:
1. 3%-5% bentonite is added into water in the mixer. When dispersed after mixing, it turns into a slurry. The slurry temperature between 60-120 degrees Fahrenheit is preferred.
2. The bitumens (asphalt coal tar or both) are heated to 250-350 degree Fahrenheit.
3. The slurry and bitumen is then combined into a mixture of emulsified bitumen through process such as dispersing type (batch to batch) or colloid mill type (continuous) system.
The specifications of emulsified asphalt meet ASTM D 1227, Standard Specification for Emulsified Asphalt Used as Protective Coating for Roofing. The Specifications of emulsified coal tar meets ASTM D 5727 Standard Specification for Emulsified Refined Coal Tar and ASTM D3320 Standard Specification for Emulsified Coal-Tar Pitch.